High-performance electroactive polymer transducers

ABSTRACT

Electroactive polymer constructions that convert electrical energy to mechanical energy and vice versa are disclosed. The subject transducers (actuators, generators, sensors or combinations thereof) share the requirement of a frame or fixture element used in preloading elastomeric film electrodes and dielectric polymer in a desired configuration. The structures are either integrally biased in a push-pull arrangement or preloaded/biased by another element.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of prior application Ser. No.11/085,804, filed Mar. 21, 2005, which is incorporated herein byreference in its entirety.

FIELD OF THE INVENTION

The present invention relates generally to electroactive polymerconstructions that convert electrical energy to mechanical energy andvice versa. More particularly, the present invention relates to frameand web configurations for pre-strained polymer actuators andtransducers.

BACKGROUND

A tremendous variety of devices used today rely on actuators of one sortor another to convert electrical energy to mechanical energy. Theactuators “give life” to these products, putting them in motion.Conversely, many power generation applications operate by convertingmechanical action into electrical energy. Employed to harvest mechanicalenergy in this fashion, the same type of actuator may be referred to asa generator. Likewise, when the structure is employed to convertphysical stimulus such as vibration or pressure into an electricalsignal for measurement purposes, it may be referred to as a transducer.Yet, the term “transducer” may be used to generically refer to any ofthe devices. By any name, a new class of components employingelectroactive polymers can be configured to serve these functions.

Especially for actuator and generator applications, a number of designconsiderations favor the selection and use of advanced electroactivepolymer technology based transducers. These considerations includepotential force, power density, power conversion/consumption, size,weight, cost, response time, duty cycle, service requirements,environmental impact, etc. Electroactive Polymer Artificial Muscle(EPAM™) technology developed by SRI International and licenseeArtificial Muscle, Inc., excels in each of these categories relative toother available technologies. In many applications, EPAM™ technologyoffers an ideal replacement for piezoelectric, shape-memory alloy (SMA)and electromagnetic devices such as motors and solenoids

As an actuator, EPAM™ technology operates by application of a voltageacross two thin elastic film electrodes separated by an elasticdielectric polymer. When a voltage difference is applied to theelectrodes, the oppositely-charged members attract each other producingpressure upon the polymer therebetween. The pressure pulls theelectrodes together, causing the dielectric polymer film to becomethinner (the z-axis component shrinks) as it expands in the planardirections (the x and y axes of the polymer film grow). Another factordrives the thinning and expansion of the polymer film. The like (same)charge distributed across each elastic film electrode causes theconductive particles embedded within the film to repel one anotherexpanding the elastic electrodes and dielectric attached polymer film.

Using this “shape-shifting” technology, Artificial Muscle, Inc. isdeveloping a family of new solid-state devices for use in a wide varietyof industrial, medical, consumer, and electronics applications. Currentproduct architectures include: actuators, motors, transducers/sensors,pumps, and generators. Actuators are enabled by the action discussedabove. Generators and sensors are enabled by virtue of changingcapacitance upon physical deformation of the material.

Artificial Muscle, Inc. has introduced a number of fundamental “turnkey”type devices can be used as building blocks to replace existing devices.Each of the devices employs a support or frame structure to pre-strainthe dielectric polymer. It has been observed that the pre-strainimproves the dielectric strength of the polymer, thereby offeringimprovement for conversion between electrical and mechanical energy byallowing higher field potentials.

Of these actuators, “Spring Roll” type linear actuators are prepared bywrapping layers of EPAM™ material around a helical spring. The EPAM™material is connected to caps/covers at the ends of the spring to secureits position. The body of the spring supports a radial orcircumferential pre-strain on the EPAM™ while lengthwise compression ofthe spring offers axial pre-strain. Voltage applied causes the film tosqueeze down in thickness and relax lengthwise, allowing the spring(hence, the entire device) to expand. By forming electrodes to createtwo or more individually addressed sections around the circumference,electrically activating one such section causes the roll extend and theentire structure to bend away from that side.

Bending beam actuators are formed by affixing one or more layers ofstretched EPAM™ material along the surface of a beam. As voltage isapplied, the EPAM™ material shrinks in thickness and growth in length.The growth in length along one side of the beam causes the beam to bendaway from the activated layer(s).

Pairs of dielectric elastomer films (or complete actuator packages suchas the aforementioned “spring rolls”) can be arranged in “push-pull”configurations. Switching voltage from one actuator to another shiftsthe position of the assembly back and forth. Activating opposite sidesof the system makes the assembly rigid at a neutral point.So-configured, the actuators act like the opposing biceps and tricepsmuscles that control movements of the human arm. Whether the push-pullstructure comprises film sections secured to a flat frame or one or moreopposing spring rolls, etc, one EPAM™ structure can then be used as thebiasing member for the other and vice versa.

Another class of devices situates one or more film sections in a closedlinkage or spring-hinge frame structure. When a linkage frame isemployed, a biasing spring will generally be employed to pre-strain theEPAM™ film. A spring-hinge structure may inherently include therequisite biasing. In any case, application of voltage will alter theframe or linkage configuration, thereby providing the mechanical outputdesired.

Diaphragm actuators are made by stretching EPAM™ film over an opening ina rigid frame. Known diaphragm actuator examples are biased (i.e.,pushed in/out or up/down) directly by a spring, by an intermediate rodor plunger set between a spring and EPAM™, by resilient foam or airpressure. Biasing insures that the diaphragm will move in the directionof the bias upon electrode activation/thickness contraction rather thansimply wrinkling. Diaphragm actuators can displace volume, making themsuitable for use as pumps or loudspeakers, etc.

More complex actuators can also be constructed. “Inch-worm” and rotaryoutput type devices provide examples. Further description and detailsregarding the above-referenced devices as well as others may be found inthe following patents and/or patent application publications: U.S. Pat.No. 6,812,624 Electroactive polymers; U.S. Pat. No. 6,809,462Electroactive polymer sensors; U.S. Pat. No. 6,806,621 Electroactivepolymer rotary motors; U.S. Pat. No. 6,781,284 Electroactive polymertransducers and actuators; U.S. Pat. No. 6,768,246 Biologically poweredelectroactive polymer generators; U.S. Pat. No. 6,707,236 Non-contactelectroactive polymer electrodes; U.S. Pat. No. 6,664,718 Monolithicelectroactive polymers; U.S. Pat. No. 6,628,040 Electroactive polymerthermal electric generators; U.S. Pat. No. 6,586,859 Electroactivepolymer animated devices; U.S. Pat. No. 6,583,533 Electroactive polymerelectrodes; U.S. Pat. No. 6,545,384 Electroactive polymer devices; U.S.Pat. No. 6,543,110 Electroactive polymer fabrication; U.S. Pat. No.6,376,971 Electroactive polymer electrodes; U.S. Pat. No. 6,343,129Elastomeric dielectric polymer film sonic actuator; 20040217671 Rolledelectroactive polymers; 20040263028 Electroactive polymers; 20040232807Electroactive polymer transducers and actuators; 20040217671 Rolledelectroactive polymers; 20040124738 Electroactive polymer thermalelectric generators; 20040046739 Pliable device navigation method andapparatus; 20040008853 Electroactive polymer devices for moving fluid;20030214199 Electroactive polymer devices for controlling fluid flow;20030141787 Non-contact electroactive polymer electrodes; 20030067245Master/slave electroactive polymer systems; 20030006669 Rolledelectroactive polymers; 20020185937 Electroactive polymer rotary motors;200201.75598 Electroactive polymer rotary clutch motors; 20020175594Variable stiffness electroactive polymer systems; 20020130673Electroactive polymer sensors; 20020050769 Electroactive polymerelectrodes; 20020008445 Energy efficient electroactive polymers andelectroactive polymer devices; 20020122561 Elastomeric dielectricpolymer film sonic actuator; 20010036790 Electroactive polymer animateddevices; 20010026165 Monolithic electroactive polymers;

Each of these publications is incorporated herein by reference in itsentirety for the purpose of providing background and/or further detailregarding underlying technology and features as may be used inconnection with or in combination with the aspects of present inventionset forth herein.

While the devices described above provide highly functional examples ofEPAM™ technology transducers, there continues to be an interest indeveloping more efficient EPAM™ transducers. The gains in efficiencyoffered by transducers according to the present invention may come interms of preloading improvement, interface with driven/drivingcomponents, output, manufacturability, etc. Those with skill in the artwill appreciate the applicable advantages.

SUMMARY OF THE INVENTION

The present invention offers a number of EPAM™ transducer designs toaugment the line of “turn-key” tools offered by the assignee hereof(Artificial Muscle, Inc.). The designs all share the requirement of aframe or fixture element used in preloading the elastomeric filmelectrodes and dielectric polymer in a desired configuration.

Certain of the embodiments include push-pull subassemblies. Aspects ofthe invention may incorporate a complex frame structure to marrydifferent types of actuators. Another aspect of the invention includesframe structures with alternative push-pull actuator configurations forin-plane and/or out-of-plane input/output. Still other aspects of theinvention are directed toward producing more robust and/or easilymanufactured actuator structures. In this regard, frustum-shapeddiaphragm actuators are produced in which the top of the structureincludes a cap. The cap may be a solid disc, annular or otherwiseconstructed. The cap provides a stable interface between opposingfrustums and/or for a mechanical preloaded element such as a spring.Also included in the invention are advantageous applications for thesubject transducer structures.

One such application is for a pump. The pump may use a single-frustumactuator or a double-frustum actuator design. In the former case, thefrustum cap provides a stable surface against which to mechanically biasthe structure. Such a structure can be made very robust as well ascompact. A double-frustum design requires no additional preload source.Further, it may be configured to serve as a double-acting pump. Inaddition, use of two actuators arranged in series offers the potentialto double the stroke. Other in-series actuator arrangements arecontemplated in the present invention as well.

Another application is for a camera in which lens position ismanipulated by a frustum-type actuator. Again, either a single ordouble-frustum design may be employed. A double frustum approach may bedesirable from the perspective of using one of the sides for positionsensing and preload, and another for actuation. Another cameraapplication uses the complex frame in which a frustum-type actuatorcontrols lens position and one or more planar actuator sections controlzoom.

Other potential applications of the subject transducers include valves,or valve control components, speaker diaphragms, multi-axis positionsensors/joysticks, vibrators, haptic or force feedback control devices,multi-axis actuators, etc.

A “frustum” is technically the portion of a geometric solid that liesbetween two parallel planes A frustum is often regarded as the basalpart of a cone or pyramid formed by cutting off the top by a plane,typically, parallel to the base. Naturally, frustum-type actuatorsaccording to the invention may be in the form of a truncated cone,thereby having a circular cross-section, or may employ a variety ofcross-sectional configurations

Depending on their application, desirable alternative cross-sectionalgeometries include triangular, square, pentagonal, hexagonal, etc.Often, symmetrically shaped members will be desirable from theperspective of consistent material performance. However, ovaloid,oblong, rectangular or other shapes may prove better for a givenapplication—especially those that are space-constrained. Furthervariation of the subject “frustum” transducers is contemplated in thatthe top and/or bottom of the form(s) need not be flat or planer, normust they be parallel. In a most general sense, the “frustum” shapeemployed in the present invention may be regarded as a body of volumethat is truncated or capped at an end. Often this end is the one havingthe smaller diameter or cross-sectional area.

The various devices describe may be driven by the specific actuatorsdescribed herein or by others. Yet, all of the devices incorporate adiaphragm in their design. Advantageously, the actuator cap and devicediaphragm are one in the same, thereby integrating the subassemblies.

BRIEF DESCRIPTION OF THE DRAWINGS

The figures illustrate exemplary aspects of the invention. Of thesefigures:

FIGS. 1A and 1B show opposite sides of an EPAM™ layer;

FIG. 2 is an assembly view of an EPAM™ layer stack

FIG. 3 is an assembly view of an EPAM™ planar actuator;

FIGS. 4A and 4B are assembly and perspective views, respectively, of aplanar transducer configuration;

FIG. 5 is a top view of a the device in FIGS. 4A and 4B electricallyconnected for planar actuation;

FIGS. 6A and 6B are assembly and perspective views, respectively, of thetransducer in FIGS. 4A and 4B setup in an alternate, frustumconfiguration for out-of-plane actuation;

FIGS. 7A-7C diagrammatically illustrate the geometry and operation offrustum-shaped actuators

FIG. 8 is a top view of a multi-phase frustum-shaped actuator;

FIG. 9A is an assembly view of another frustum shaped actuator, and FIG.9B is a side view the same basic actuator with an alternate frameconstruction;

FIG. 10 is a sectional perspective view of a parallel-stacked type offrustum transducer;

FIG. 11 is a side-section view showing an optional output shaftarrangement with a frustum type transducer;

FIG. 12 is a side-section view of an alternate, inverted frustumtransducer configuration;

FIG. 13 is a sectional perspective view of a coil spring-biased singlefrustum transducer;

FIG. 14 is a perspective view of a leaf spring-biased single frustumtransducer;

FIG. 15 is a perspective view of a weight-biased single frustumtransducer;

FIG. 16 is a perspective view of frustum-type transducers provided inseries for stroke amplification;

FIG. 17 is a perspective view of a reconfigurable exploratory systemoffering transducers of various types, and FIGS. 18A-18C are assemblyviews of various alternative configurations for the system in FIG. 17;

FIG. 19A is a sectional perspective view of a camera lens assemblyemploying an frustum actuator for control focus, and

FIG. 19B is an assembly view of camera components with the system shownin FIG. 19A;

FIG. 20 is a sectional perspective view of a camera lens assemblyemploying another type of frustum actuator for focus control;

FIG. 21A is a sectional perspective view of another camera lens assemblyemploying an actuator combination to control each of zoom and focus, andFIG. 21B is an assembly view of camera components with the system shownin FIG. 21A;

FIGS. 22A and 22B are perspective views showing an alternative means ofcontrolling zoom, and FIGS. 23A-23C are perspective views showingprogressive stages of actuation of the transducer arrangement in FIGS.22A and 22B;

FIG. 24A is an assembly view of a valve mechanism; FIGS. 24B and 24C areside-sectional views of the valve in FIG. 24A illustrating valveactuation;

FIGS. 25-27 are side-sectional views of different valve configurations;

FIG. 28 is a side-sectional view of a pressure measurement transduceraccording to the invention;

FIG. 29A is a side sectional view of an active check valve; FIG. 29B isa perspective view of the structure shown in FIG. 29A;

FIGS. 30A and 30B are side-sectional views of an inline valve set withinan application-specific housing;

FIGS. 31A and 31B are sectional perspective views showing variations ofa first pump employing frustum-type actuators;

FIGS. 32 and 33 are sectional perspective views showing other pumpvariations employing frustum-type actuators;

FIG. 34 is a perspective view of an integrated flow control systememploying various of the valves and pumps illustrated above;

FIG. 35 is a perspective assembly view showing a pump housing withintegrated check valves formed in conjunction with the pump diaphragm;

FIG. 36 is a perspective assembly view showing another pump assemblyincorporating check valves;

FIG. 37 is a perspective view of a vibrator element;

FIG. 38 is a sectional perspective view of a haptic feedback controller;and

FIG. 39 is a perspective view on a speaker system employing a pluralityof frustum and/or double-frustum transducers.

Variation of the invention from that shown in the figures iscontemplated.

DETAILED DESCRIPTION OF THE INVENTION

Various exemplary embodiments of the invention are described below. Anumber of actuator/transducer embodiments are first described. Next,systems optionally incorporating such devices are described. Finally,manufacturing techniques and applicable methods of use and kits aredescribed, followed by discussion of contemplated variations. Referenceis made to these examples in a non-limiting sense. They are provided toillustrate more broadly applicable aspects of the present invention.

Transducers

FIGS. 1A and 1B show opposite sides of an EPAM™ layer 10. The layercomprises dielectric polymer sandwiched between elastic thin filmelectrodes. FIG. 1A shows the side of the layer patterned with “hot”electrodes 12 and 14. Each electrode is connected to a lead 16. FIG. 1Bshows the opposite side of layer 10 patterned with a common “ground”electrode 18 connected to a single lead 16.

As shown in FIG. 2, multiple film layers 10 are stacked and held in astretched state within frame pieces 20. A number of individual EPAM™layers 10 are advantageously stacked to form a compound layer 10′. Doingso amplifies the force potential of the system. The number of layersstacked may range from 2 to 10 or more. Generally, it will be desired tostack an even number of layers so that ground electrodes are facing anyexposed surfaces to provide maximum safety. In any case, the EPAM™ layeror layers may collectively be referred to as EPAM™ “film”.

With one or more layers of material secured in a frame, the frame may beused to construct a complex transducer mechanism. FIG. 3 shows one suchconstruction known in the art. Here, individual cartridge sections 22are secured to a secondary or body frame portion 24. Any film frames andintermediate frame member are joined to provided a combined (i.e.,attached with fasteners as shown, bonded together, etc.) frame structure26. A spacer 28 provides an interface for an input/output rod 30received by the frame through guide hole 32. The spacer is attached tothe film via complementary mounts 34 bonded to or clamped the EPAM™ filmwith the spacer.

To actuate a device constructed according to FIG. 3, voltage is appliedto either one of electrodes 12 or 14. By applying voltage to one side,that side expands, while the other relaxes its preload and contracts.Other modes of actuation are referenced to above.

A first device according to the present invention can be similarlyconfigured and operated. FIGS. 4A and 4B provide assembly andperspective view of a transducer 40 according to the present inventionthat can alternatively be configured for planar actuation (as the deviceis in FIG. 3) and out-of-plane actuation. As with the device describedin reference to the previous figures, frames 20 carry layers 10/10′ withground electrodes facing outward.

Again, individual cartridge sections 22 are stacked with a secondaryframe 24 and spacer 28 therebetween, with the spacer providing aninterface for an input/output rod 30 received by the frame. However,spacer 28 in this configuration is to be attached to a substantiallysquare-shaped cap 42 elements. A more symmetrical interface portionoffers advantages as will be explained below. FIG. 4B shows theassembled device. Here frame 26 is shown as a complete unit.

As for actuation of the device, FIG. 5 shows a basic circuit diagram inwhich A and B sides of the circuit are powered relative to ground tocause back and forth movement of rod 30 along an X-axis relative toframe.

Yet, in an alternative configuration, the same EPAM™ layer cartridgescan be used to produce a transducer adapted for out-of-plane or Z-axisinput/output. FIGS. 6A and 6B illustrate such a device. Here transducer50 assembly may employ a thicker body frame 24′. By employing such aframe and by omitting spacer, when caps 42 are secured to one another,they produce deeply concave forms 52 facing opposite or away from oneanother. To actuate the transducer for simple Z-axis motion, one of theconcave/frustum sides is expanded by applying voltage while the otherside is allowed to relax. Such action increases the depth of one concaveform while decreasing that of the other. In the simplest case, themotion produced is generally perpendicular to a face of the cap.

FIGS. 7A-7C diagrammatically illustrate the manner in which theseconcave/convex or frustum shaped actuators function in a simplified twodimensional model. FIG. 7A illustrates the derivation of the transducerfrustum shape. Whether conical, squared, ovaloid, etc. when viewed fromabove, from the side a truncated form 60 is provided by modifyingexisting diaphragm actuator configurations by capping the top (orbottom) of the structure. When under tension, the cap 42 alters theshape the EPAM™ layer/layers 10/10′ would take. In the example where apoint load stretches the film, the film would assume a conical shape (asindicated by dashed lines define a triangular top 62). However, whencapped or altered to form a more rigid top structure, the form istruncated as indicated in solid lines 64 in FIG. 7A.

So-modifying the structure fundamentally alters its performance. Forone, it distributes stress that would otherwise concentrate at thecenter of structure 66 around a periphery 68 of the body instead. Inorder to effect this force distribution, the cap is affixed to the EPAM™layers. An adhesive bond may be employed. Alternatively, the constituentpieces may be bonded using any viable technique such as thermal bonding,friction welding, ultrasonic welding, or the constituent pieces may bemechanically locked or clamped together. Furthermore, the cappingstructure may comprise a portion of the film that is made substantiallymore rigid through some sort of thermal, mechanical or chemicaltechniques—such as vulcanizing.

Generally, the cap section will be sized to produce a perimeter ofsufficient length to adequately distribute stress applied to thematerial. The ratio of size of the cap to the diameter of the frameholding the EPAM™ layers may vary. Clearly, the size of disc, square,etc. employed for the cap will be larger under higher stress/forceapplication. The relative truncation of the structure (as compared topoint-loaded cones, pressure biased domes, etc.) is of furtherimportance to reduce volume the aggregate volume or space the transduceroccupies in use, for a given amount of pre-stretch to the EPAM™ layers.Furthermore, in a frustum type diaphragm actuator, the cap or diaphragm42 element may serve as an active component (such as a valve seat, etc.in a given system).

With the more rigid or substantially cap section formed or set in place,when EPAM™ material housed by a frame is stretched in a directionperpendicular to the cap (as seen by comparing the EPAM/frameconfigurations as shown in FIGS. 4A/4B and 6A/6B), it produces thetruncated form. Otherwise the EPAM™ film remains substantially flat orplanar.

Returning to FIG. 7A, with the cap 42 defining a stable top/bottomsurface, the attached EPAM™ polymer sides 10/10 of the structure assumean angle. The angle α the EPAM™ is set at when not activated may rangebetween 15 and about 85 degrees. More typically it will range from about30 to about 60 degrees. When voltage is applied so that the EPAM™material is compressed and grows in its planar dimensions, it assumes asecond angle β in about the same range plus between about 5 and 15degrees. Optimum angles may be determined based on applicationspecifications.

Single-sided frustum transducers are within the contemplated scope ofthe present invention as well as double-sided structures. For preload,single sided devices employ any of a spring interfacing with the cap(e.g., a coil, a constant force or roll spring, leaf spring, etc.), airor fluid pressure, magnetic attraction, a weight (so that gravityprovides preload to the system), or a combination of any of these meansor others.

In double-sided frustum transducers, one side typically provides preloadto the other. Still, such devices may include additional biasfeatures/members. FIG. 7B illustrates the basic “double-frustum”architecture 70. Here, opposing layers of EPAM™ material or one side ofEPAM™ film and one side of basic elastic polymer are held together undertension along an interface section 27. The interface section oftencomprises one or more rigid or semi-rigid cap element(s) 42. However, byadhering two layers of the polymer together at their interface, thecombined region of material, alone, offers a relatively stiffer or lessflexible cap region in the most basic manner to offer a stable interfaceportion of the transducer.

However constructed, the double-frustum transducer operates as shown inFIG. 7B. When one film side 74 is energized, it relaxes and pulls withless force, releasing stored elastic energy in the bias side 74 anddoing work through force and stroke. Such action is indicated by dashedline in FIG. 7B. If both film elements comprise EPAM™ film, then theactuator can move in/out or up/down relative to a neutral position(shown by solid line in each of FIGS. 7A and 7B) as indicated bydouble-headed arrow 80.

If only one active side 74/76 is provided, forced motion is limited toone side of neutral position 82. In which case, the non-active side ofthe device may simply comprise elastic polymer to provide preload/bias(as mentioned above) or EPAM™ material that is connected electrically tosense change in capacitance only or to serve as a generator to recovermotion or vibration input in the device in a regenerative capacity.

Further optional variation for transducers according to the presentinvention includes provision for multi-angle/axis sensing or actuation.FIG. 8 shows a circular EPAM™ cartridge 90 configuration with three (92,94, 96) independently addressable zones or phases. When configured as anactuator, by differential voltage application, the sections will expanddifferently causing cap 42 to tilt on an angle. Such a multi-phasedevice can provide multi-directional tilt as well as translationdepending on the manner of control. When configured for sensing, inputfrom a rod or other fastener or attachment to the cap causing angulardeflection can be measured by way of material capacitance change.

The EPAM™ section shown in FIG. 8 is round. FIG. 9A provides an assemblyview of a round-frustum transducer 100. The body frame member 24employed is solid, resembling that used in the combination orconvertible type actuator shown in FIGS. 4A-6B above. However, thedevice shown in FIG. 9A is a dedicated diaphragm type actuator (thoughit may employ a multi-phase structure shown in FIG. 8.) An alternativeconstruction for such an actuator is shown in FIG. 9B. Here, themonolithic frame element 24 is replaced by simple frame spacers 24″.

FIG. 10 shows another construction variation in which the transducercomprises multiple cartridge layers 22 on each side of a double-frustumdevice 100. Individual caps 42 are ganged or stacked together. Toaccommodate the increased thickness, multiple frame sections 24 maylikewise be stacked upon one another.

Recall that each cartridge 22 may employ compound EPAM™ layers 10′.Either one or both approaches—together—may be employed to increase theoutput potential of the subject device. Alternatively, at least onecartridge member in the of the stack (on either one or both sides of thedevice) may be setup for sensing as opposed to actuation to facilitateactive actuator control or operation verification. Regarding suchcontrol, any type of feedback approach such as a PI or PID controllermay be employed in such a system to control actuator position with veryhigh accuracy and/or precision.

FIG. 11 is a side-section view showing an optional output shaftarrangement with a frustum type transducer 110. Threaded bosses 112 oneither side of the cap pieces provide a means of connection formechanical output. The bosses may be separate elements attached to thecap(s) or may be formed integral therewith. Even though an internalthread arrangement is shown, external threaded shaft may be employed.Such an arrangement may comprise a single shaft running through thecap(s) and secured on either side with a nuts in a typical jam-nutarrangement. Other fastener or connection options are possible as well.

FIG. 12 is a side-section view of an alternate transducer 120configuration, in which instead of employing two concave structuresfacing away from one another, the two concave/frustum sections 122 facetowards each other. The preload or bias on the EPAM™ layers to force thefilm into shape is maintained by a shim or spacer 124 between caps 42.As shown, the space comprises an annular body. The caps may too includean opening in this variation of the invention as well as others. Notealso that the inward-facing variation of the invention in FIG. 12 doesnot require an intermediate frame member 24 between individual cartridgesections 22. Indeed, the EPAM™ layers on each side of the device cancontact one another. Thus, in situations where mounting space islimited, this variation of the invention may offer benefits. Furtheruses of this device configuration are also discussed below. Otherbiasing approaches for frustum-type actuators are, however, firstdescribed.

Specifically, FIG. 13 provides a sectional perspective view of a coilspring-biased single frustum transducer 130. Here, a coil spring 132interposed between cap 42 and a baffle wall 134 associated with theframe (or part of the frame itself) biases the EPAM™ structure. In thetransducer 140 shown in FIG. 14, a leaf spring 142 biases the capportion of a transducer. The leaf spring is shown attached to a boss 144by a bolt 146 or a spacer captured between the bold and a nut (notshown) on the other side of the cap. The ends of the leaf are guided byrails 148. In another transducer example 150 illustrated by FIG. 15 theEPAM™ film may be biased by a simple weight 152 attached to or formedintegral with the cap(s) 42. Though the device is shown tilted up forthe sake of viewing, it will typically be run flat so that the pull ofgravity on the weight symmetrical biases the transducer along a Z-axis.

Based on the above, it should be apparent that any number of parametersof the subject transducers can be varied to suit a given application. Anon-exhaustive list includes: the output fastener or connection meansassociated with the cap (be it a threaded boss, spacer, shaft, ring,disc, etc.); prestrain on the EPAM™ film (magnitude, angle or direction,etc.); film type (silicone, acrylic, polyurethane, etc.); filmthickness; active vs. non-active layers; number of layers; number offilm cartridges; number of phases; number of device “sides” anddirection of device sides.

Systems

Any of the subject transducers can be employed in more complexassemblies. FIG. 16 provides a transducer example 160 in which a numberof frustum-type transducer subunits 100 are stacked in series for strokeamplification. What is more, an inward facing double-frustum transducers120 offers a second output phase through attachment to its frame 20.While the height of this member is stable due to its internal space(referenced above), the position of its frame is mobile to providesecond stage output or input.

Instead of a center stage 120, a simple spacer may be employed betweenthe outer transducers 100 for basic stroke amplification purposes. Tofurther increase stroke, then, another such stack may be set on thefirst, etc. To offer another stage of actuation, another inward-facingtransducer may be employed, etc. Yet another variation contemplatespairing an inward facing transducer with an outward facing transducer inactuator sensor pairs. Naturally, other combinations are within thescope of the present invention.

Another highly flexible problem-solving or experimental approach offeredby the present invention is illustrated in connection with FIG. 17. Herea reconfigurable exploratory system 170 is shown that offers transducersof various types. FIGS. 18A-18C provide assembly views of variousalternative configurations for the system in FIG. 17. With a componentstack arrangement 172 as shown in FIG. 18A, system 170 is adapted toserve as a planar actuator. With a component stack arrangement 174 asshown in FIG. 18B, system 170 is adapted to serve as a diaphragmactuator. With a component stack arrangement 176 as shown in FIG. 18C,system 176 is adapted to operate as a diaphragm pump. Such a pump isdescribed in further detail below. As for system 170, suffice it to say,here, that the subject architecture lends itself to tremendousflexibility.

FIG. 19A provides a view of another application employing the presentinvention. The figure details a camera lens assembly 180 employing afrustum-type actuator 182 to control focus. The cap or diaphragm of thetransducer 184 is open in the shape of a ring for light to pass to alens 186 the may be set in a housing 188. A leaf spring 190 is shown incontact with the housing to bias the EPAM™ film.

As shown in FIG. 19B, a completed camera assembly will include at leasta shroud or cover 192, internal frame component(s) 194, a CCD 196(Charge-Couple Device) for image capture and electronics 198. Theelectronics may be integrated to drive the entire device, or theelectronics on board 200 may simply provide the voltage step-up andcontrol required for the EPAM™ actuator.

Suitable power supply modules for such use include EMCO High VoltageCorp. (California) Q, E, F, G models and Pico Electronics, Inc. (NewYork) Series V V units. Naturally, a custom power supply could beemployed. In any case, the referenced power supplies may be employed notonly in the camera embodiments, but any system incorporating the subjecttransducers.

FIG. 20 shows another camera lens assembly 226. Instead of a leafspring, however, this design employs a double-frustum type actuator 100in which the preload side of the device 228 may not be EPAM™ film, butsimply an elastomeric web. Should side/layer 228 comprise EPAM™material, however, it may most advantageously employed for sensingposition by capacitance change.

In another variation of the invention, FIG. 21A shows a camera lensassembly 210 employing an actuator combination 212 to control each ofzoom and focus. As before, the device includes a focus stage driven by adiaphragm actuator 214 according to the present invention. In addition,the device includes a zoom stage set of planar actuators 216. Generallyfocus adjustment requires between 0.1 and 2.0 mm movement; zoom oftenrequires 5 to 10 times that amount of stroke.

Accordingly, zoom is handled by a different type of actuator. In FIG.21A, zoom function is actuated by a pair of planar-type transducers 216located across from one another. Of interest is that each of the planarand diaphragm actuators are formed by EPAM™ film stretched over or upona common frame element 218. Such functionality is offered by thetwo-lens arrangement shown. Zoom is accomplished varying the distancebetween lens 186 and lens 220. Bulk movement of lens 220 relative tolens 186 is accomplished by arms 222 connected to zoom lens frame 224.

A combined-use frame offers another option according to the inventionthat may be applied in any circumstance where bulk movement and finetuning is required, or where (as in a camera) separate motion componentsare desired. Though not shown, it also is contemplated that multiplefaces of a combined frame may carry diaphragm actuators alone or planaractuators alone. Still further, non-orthogonal frame geometry may beemployed.

Regarding camera applications of the present invention, theaforementioned systems can be made extremely compact. As such, they areparticularly suitable for use in compact digital or cell phone cameras,etc.

In cases where there is more available space, it may be desired toprovide an EPAM™ zoom/focus engine suitable for longer zoom travel toincrease the operating range of the device. FIGS. 22A and 22B areperspective views showing an alternative planar camera system 230 inwhich a telescopic arrangement 232 of planar actuators is provided forcontrolling zoom. These figures show minimum and maximum zoom positionsas indicated by arrows 232 and 234, respectively.

The manner in which the actuators are connected and operate is clarifiedby the enlarged section views provided by FIGS. 23A-23C showing stagesof the transducer stack actuation. The progressive motion is achieve byconnection of successive output bars 238 (partially hidden) to framesections 20 with the final output bar 340 and attached rod 30 left tofloat or, rather, to drive zoom components.

The present invention further comprises a number of flow control means.These means include valves, mixers and pumps.

FIG. 24A is an assembly view of a valve mechanism. Valve 240 comprisesthe elements the make up a double-frustum type actuator 100 as discussedabove. Namely, valve comprises EPAM™ film stretched within framemembers, and secured by cap(s). In addition, valve 240 includes a cover242 with fittings 244, 246 received therein.

FIGS. 24B and 24C are side-sectional views of the valve in FIG. 24Aillustrating valve actuation. In FIG. 24B the valve is closed. Cap/caps42 serve as a diaphragm blocking the operative fitting 244 in an“normally closed” configuration in a neutral film (powered or unpowered)condition. In FIG. 24C, the valve is opened by actuating the transducerto drive cap 42 in the direction of arrow 248 to allow flow through achamber 250 formed within the device.

FIG. 25 shows another one-sided double-frustum diaphragm valve 260. Thedevice differs only in that a tapered needle valve arrangement 262 isprovided in order to offer a wider range of control.

FIG. 26 shows a three-way mixing valve 270. Inlet fittings 272 areconnected to lines (not shown) in fluid communication with differentfluid/gas sources (not shown). Exit fittings 274, 276 are connected to acommon outlet line (not shown). The position of the cap/diaphragm 42which may vary as indicated by double arrow 278 dictates the proportionof each different flow able to enter the exits fittings. Naturally, thisdevice may also include tapered needle valves like the preceding deviceas may the other valves described herein.

FIG. 27 shows an in-line valve 280. Where there previous valves employan imperforate diaphragm, diaphragm 282 in this case includes throughholes 284. In this manner, fluid is able to pass from one side of thedevice to the other through fittings 286, 288, where diaphragm 282modulates the amount of flow able to pass by or into the operativefitting 288.

FIG. 28 is a side-sectional view of a pressure measurement transducer290 according to the invention. Fluid pressure entering a chamber 292 issensed by correlation to changes in capacitance caused by stretching theEPAM™ film. As compared to a typical EPAM™ diaphragm transducer, cap 42offers a new level of robustness to the system.

FIGS. 29A and 29B illustrate a variable “cracking pressure” check valve294. The EPAM™ material of actuator 296 is stretched so that cap seatsat the distal end of valve stem 244 with some pressure. When voltage isapplied to the material, it contracts in thickness, and extends in thedirection of arrow 298, thus reducing the preload at the valveinterface. When so-relaxed, fluid at a relatively lower pressure is ableto escape past cap 42 (or valve needle, etc.) and exit through fitting246.

FIGS. 30A and 30B offer views of inline valve configuration 300 in whichthe frustum-type valve 302 is set within an application-specific housing304. In this case, the housing is configured to replace a vapor canisterpurge valve used in internal combustion engine applications. FIG. 30Ashows the valve in a closed configuration; FIG. 30B shows the valve inan open configuration. The valve is normally closed, and open uponvoltage application to the EPAM™ film. The valve includes a stem 306integrated with cap or diaphragm 308. Instead of a employing adouble-frustum design for bias, a coil spring 310 is employed in asingle-sided design.

As for other applications of the subject systems a number of pumps areillustrated next. The pumps may be utilized for fluid or gas transferunder pressure, or used to generate vacuum. Valve structures may be fitto the pump bodies or integrated therein/therewith.

FIGS. 31A and 31B show variations of a first pump 320 and 320′ employingdouble frustum-type actuators 100. Each device comprises a singlechamber 322 diaphragm pump. The EPAM™ actuator section may be setup forsingle or two-phase actuation as discussed above in connection with thevarious double-frustum transducer designs. The pump includes a pair ofpassive check valves 324, 326 in which movement of a membrane 328 urgedby fluid (including gas) pressure alternatively opens and closes thevalves as readily apparent.

Pump 320′ in FIG. 31B is identical to that in FIG. 31A except that itincludes a diaphragm wall 330 in addition to the cap/diaphragm 42portion. Wall 330 provides an overall improved chamber wall interface(e.g., one the is less susceptible to elastic deformation, offeringbetter material compatibility with caustic chemicals, etc.) than theEPAM EPAM™ film itself as employed in the previous pump variation.

Like the previous devices, pump 340 shown in FIG. 32 employs passivecheck valves 324, 326. It differs from the devices, however, in that itembodies an integrated double chamber 342, 344 or double-acting pump.Again, the actuator may be a one-phase or two-phase type transducer.

FIG. 33 shows a one chamber pump 350. Of course it could be reconfiguredinto a two-chamber design as in pump 340 in FIG. 32. Of interest,however, is that the check valves employed in this device are notpassive, but rather EPAM™ valves 352, 354 similar to or as describedabove in connection with FIG. 28. Naturally, other EPAM™ valveconfigurations may be utilized (e.g., the arrangement shown in FIGS.24A-24C).

In essence, FIG. 33 offers one illustration of the assembly of variousfluid flow subcomponents to create an integrated EPAM™ controlled deviceoffering numerous advantages over known systems. FIG. 34 illustrates howthe subject devices may be combined with themselves or other devicesaccording to the present invention to offer a system of even greaterutility. A “complete” fluid handling system 360 as illustrated in FIG.34 comprises a pump 350, flow control valve 280 and/or a pressure sensor290. Naturally, such a system will be plumbed with tubing asappropriate—perhaps as indicated by arrows 362. One potentialapplication of such a system may be in filling or controlling the filllevel of a bladder or reservoir (not shown) as a lumbar support in anautomobile seat. Certainly, other applications and system configurationsare possible as well. Generally speaking, pump chambers may be connectedin series to increase pressure levels attained in pumping, or connectedin parallel to increase pumping volume. An array of pumps may, likewise,be provided in using a combination of such connectivity.

Still further, certain pump or flow connection features may beintegrated into the design of the actuator itself. FIG. 35 provides anexample of a pump 400 in which flow conduits 402 are integrated in thedevice structure. EPAM™ 10/10′ film stretches to form each of thefrustum/truncated diaphragm sections 60 and portions of check valves404. Discs 406 are attached to the film and are preloaded against valveseats 408 by the tension in the film. Fluid flows through the centers ofthe discs when they lift off their seats. The discs 406 are bonded tothe film, one on each side of the film.

Such a structure is highly advantageous from the perspective of usingthe same film to define both the pump and actuator in single flowsystem. Still further, by offsetting the valve structure to the side ofthe transducer body, the overall structure is minimized in thickness.This form-factor may be desired in certain applications where “thinner”designs are desired.

FIG. 36 shows yet another example of a pump 410. Here, check valves 412are formed in a side plate assembly 414 of a pump housing. Such a designoffers a modular and compact approach for applying the basic transducerarchitecture in a pump application. Furthermore, this design offerspotential for a smaller “footprint” as compared the design in FIG. 35.While a second side plate 416 may simply be provided to complete theassembly two check-valve type plates may instead be used to provide adouble-acting pump similar in concept to that shown in FIG. 32.

Regarding other potential applications of the subject technology, FIG.37 shows a vibrator type device 370. In a double-frustum actuatorconfiguration, reciprocal movement of a mass 372 is transmitted to alarger device housing connected to the transducer frame 26.

Whether or not a mass element is provided to generate vibration or not,another application of the subject transducer is shown in FIG. 38 for ahaptic feedback controller 380. The controller may be a game consoledevice with a “joy stick” 382 that transmits vibration generator fortactile or force feedback to a user. In another variation, the joystickis attached to a multi-phase transducer 384 that by virtue ofcapacitance change upon deformation is able to sense or signal usermanipulation in the user input or control means. Such a device wouldhave applications ranging from game console construction to providing asurgeon a highly accurate interface to facilitate robotic surgery.

Finally, FIG. 39 illustrates a variation of the present invention inwhich a speaker system 390 is provided that employs a plurality offrustum and/or double-frustum transducers 392, 394, 396. A “tweeter”driver 392 is smallest, followed by a larger “mid-range” driver 394 andfinally by a large “woofer” driver 396. By virtue of the improvedperformance of the frustum geometry, both large and small (low and highfrequency tuned) speaker can be produced. They can be driven at highpower and still offer a light-weigh high performance speaker because nohefty magnets or coils are required as in typical electromagneticspeakers. What is more, the low profile of the transducers lendthemselves to variation in speaker cabinet 398 design to offeruncompromised options in styling to the audiophile.

Manufacture

Regardless of the configuration selected for the subject transducers,various manufacturing techniques are advantageously employed.Specifically, it is useful to employ mask fixtures (not shown) toaccurately locate masks for patterning electrodes for batchconstruction. Furthermore, it is useful to employ assembly fixtures (notshown) to accurately locates multiple parts for batch construction.Other details regarding manufacture may be appreciated in connectionwith the above-referenced patents and publication as well as generallyknow or appreciated by those with skill in the art.

Methods

Methods associated with the subject devices are contemplated in whichthose methods are carried out with EPAM™ actuators. The methods may beperformed using the subject devices or by other means. The methods mayall comprise the act of providing a suitable transducer device. Suchprovision may be performed by the end user. In other words, the“providing” (e.g., a pump) merely requires the end user obtain, access,approach, position, set-up, activate, power-up or otherwise act toprovide the requisite device in the subject method

Kits

Yet another aspect of the invention includes kits having any combinationof devices described herein—whether provided in packaged combination orassembled by a technician for operating use, instructions for use, etc.

A kit may include any number of transducers according to the presentinvention. A kit may include various other components for use with thetransducers including mechanical or electrical connectors, powersupplies, etc. The subject kits may also include written instructionsfor use of the devices or their assembly.

Instructions of a kit may be printed on a substrate, such as paper orplastic, etc. As such, the instructions may be present in the kits as apackage insert, in the labeling of the container of the kit orcomponents thereof (i.e., associated with the packaging orsub-packaging) etc. In other embodiments, the instructions are presentas an electronic storage data file present on a suitable computerreadable storage medium, e.g., CD-ROM, diskette, etc. In yet otherembodiments, the actual instructions are not present in the kit, butmeans for obtaining the instructions from a remote source, e.g. via theInternet, are provided. An example of this embodiment is a kit thatincludes a web address where the instructions can be viewed and/or fromwhich the instructions can be downloaded. As with the instructions, thismeans for obtaining the instructions is recorded on suitable media

Variations

As for other details of the present invention, materials and alternaterelated configurations may be employed as within the level of those withskill in the relevant art. The same may hold true with respect tomethod-based aspects of the invention in terms of additional acts ascommonly or logically employed. In addition, though the invention hasbeen described in reference to several examples, optionallyincorporating various features, the invention is not to be limited tothat which is described or indicated as contemplated with respect toeach variation of the invention. Various changes may be made to theinvention described and equivalents (whether recited herein or notincluded for the sake of some brevity) may be substituted withoutdeparting from the true spirit and scope of the invention. Any number ofthe individual parts or subassemblies shown may be integrated in theirdesign. Such changes or others may be undertaken or guided by theprinciples of design for assembly.

Also, it is contemplated that any optional feature of the inventivevariations described may be set forth and claimed independently, or incombination with any one or more of the features described herein.Reference to a singular item, includes the possibility that there areplural of the same items present. More specifically, as used herein andin the appended claims, the singular forms “a,” “an,” “said,” and “the”include plural referents unless the specifically stated otherwise. Inother words, use of the articles allow for “at least one” of the subjectitem in the description above as well as the claims below. It is furthernoted that the claims may be drafted to exclude any optional element. Assuch, this statement is intended to serve as antecedent basis for use ofsuch exclusive terminology as “solely,” “only” and the like inconnection with the recitation of claim elements, or use of a “negative”limitation. Without the use of such exclusive terminology, the term“comprising” in the claims shall allow for the inclusion of anyadditional element—irrespective of whether a given number of elementsare enumerated in the claim, or the addition of a feature could beregarded as transforming the nature of an element set forth in theclaims. For example, adding a fastener or boss, complex surface geometryor another feature to a “diaphragm” as presented in the claims shall notavoid the claim term from reading on accused structure. Statedotherwise, unless specifically defined herein, all technical andscientific terms used herein are to be given as broad a commonlyunderstood meaning as possible while maintaining claim validity.

1. An electroactive polymer transducer comprising: an open frame andelectroactive polymer material, wherein the polymer material isstretched into a frustum shape.
 2. A transducer comprising an open frameand at least two diaphragm layers, each diaphragm layer comprising anelectroactive polymer material extending within the frame, whereincentral portions of the diaphragm layers are coupled together andwherein the diaphragm layers are free to actuate in at least twodirections upon application of a voltage across the electroactivepolymer material.
 3. The transducer of claim 1, wherein the remainingportions of one diaphragm layer are spaced from the remaining portionsof the other diaphragm layer to form a double-frustum configuration. 4.The transducer of claim 1, wherein the coupled-together central portionsdefine a cap structure.
 5. The transducer of claim 4, wherein the capstructure has a disc configuration having a least one pass-through hole.6. The transducer of claim 1, wherein the electroactive polymer materialcomprises one of silicone, acrylic or polyurethane.
 7. The transducer ofclaim 1, wherein the electroactive polymer material comprises adielectric elastomer.
 8. The transducer of claim 1 wherein one diaphragmlayer biases the other diaphragm layer.
 9. The transducer of claim 1,wherein a spring biases at least one diaphragm layer.
 10. A devicecomprising: an open frame; and electroactive elastomer material securedwithin the frame and a region central to the elastomer material whichform a diaphragm; wherein the central region is less flexible than theelastomer material and wherein the elastomer material is stretched to aconcave or convex shape.
 11. The device of claim 10, wherein the centralregion comprises a substantially rigid cap.
 12. The device of claim 11,wherein the spring is a selected from a leaf spring and a coil spring.13. The device of claim 11, wherein the spring biases the electroactiveelastomer material out of plane.
 14. The device of claim 11, wherein thediaphragm forms a frustum structure.
 15. The device of claim 10, whereinthe central region is imperforate.
 16. The device of claim 10, whereinthe central region has an interior open section.
 17. The device of claim10, wherein device is adapted to operate as a sensor.
 18. The device ofclaim 10, wherein device is adapted to operate as an actuator.
 19. Thedevice of claim 10, comprising at least two diaphragms wherein each ofthe at least two elastomeric material sections are stretched intofrustum shapes.
 20. The device of claim 19, wherein one diaphragm biasesanother diaphragm.
 21. The device of claim 19, wherein the frustumsections face opposite one another.
 22. The device of claim 19, whereinthe frustum sections face towards one another.
 23. The device of claim19, wherein the central regions are ganged together.
 24. The device ofclaim 10, wherein the elastomeric material comprises a plurality ofindependently addressed sections.
 25. An assembly comprising a pluralityof stacked diaphragms according to claim
 10. 26. The device of claim 25,wherein the stacked diaphragms are connected in series.
 27. The deviceof claim 25, wherein the stacked diaphragms are connected in parallel.28. The device of claim 25, wherein a portion of the stacked diaphragmsfaces in one direction and another portion of the stacked diaphragmsfaces in an opposite direction.